The Anisole Tetrachloromethane Multiphoton Ionization Mass Spectrometry

Experimental studies show that when the molecules get through the process of multiphoton excitation energy, that is, elements coherently absorb two or more photons and the absorbed photon energy is above the ionization potential, ionization will happen. In this process it is often accompanied with chemical bonds breaken in molecules or ions cracked into small pieces. such interaction is called multiphoton ionization process. MS is an effective method abort multiionization and dissociation, and the time of flight mass spectrometry is the organic MS appling time of flight mass spectrometer. Multiphoton ionization mass spectrometry is studied by using the combination of the time of flight mass spectrometry technology with ionization technology. This article is to study the dissociation and ionization channles and principles for the anisole and carbon tetrachloride,which is common organic polyatomic molecules in industrial and agricultural production.Anisole which is the easiest and most representative mater in romatic ether materies is widely used for industrial and agricultural raw materials,and often used as organic solvents and pharmaceutical intermediates. Anisole has many related reports from the very early research and has been much attention. We study the dissociation channel and mechanism of anisole in the experiment using the time of flight mass spectrometer with the interaction of laser. This allows people get a deeper understanding of nature about the structure and function of the methyl ether ether group which is connected to the construction and other important photophysical and photochemical mater, that is not only for anisole and its derivatives provide the basis for the research, but also provide an important reference value by studing the other aromatic ethers. Tetrachloro-methane is also a common good chemical organic solvent; and often used as the extractive agent in chemical experiments. Because the toxicity of tetrachloro-methane would destroy certain human and animal liver, and damage the ozone layer. Therefore, dissociation of tetrachloro-methane ionization process has been subject to attention. This paper studies the the tetrachloro-methane dissociation process in determining the wavelength of the laser ionization, changs laser energy intensity and analysize this conditions the dissociation channels and mechanisms of tetrachloro-methane molecules.This paper includes four chapters. The first chapter is the introduction part, which outlines the definition and classification and characteristics of ionization and dissociation, the principles of the time of flight mass spectrometry and Gaussian03 research methods and theoretical basis. The second chapter is experimental apparatus and experimental methods, which introduces the experimental operation and data acquisition equipment and experimental procedures and experimental methods. The third chapter analysis detaily the multiphoton ionization process of anisole under 355 nm laser, and obtains dissociation of anisole is the parent ion dissociation step, which is the anisole molecule first coherently absorbs three photons to become the rich mother ion then fragments ion are dissociated. The main dissociation channel is about to eliminate the methyl, and hydrogen atom rearrangement is another dissociation channel. Meanwhile using Gaussion03 whit HF/6-31G basis set on the molecules and ions level we receive the stable structures, and we also calculate primary energy of anisole molecular ion and its dissociation products. The four chapter analysis the multiphoton ionization process of tetrachloro-methane, and discusse the carbon tetrachloride molecules multiphoton ionization dissociation channels and dissociation fragment ion channels. The results show that the main tetrachloro-methane dissociation channel is the mother molecular absorbs three photons to reach the electronic excited state, then dissocate into the neutral fragment ions rapidly. The CCl is the main access channel and C channel is the secondary channel.